Evidence for Starspots on DK Draconis (HR 4665) .

Observations of the long-period RS CVn-type binary DK Dra from February through September 1978 are presented. Light variations appear to be quasisinusoidal with a period of 64.6 + or - 0.4 d, and cycle-to-cycle changes in the character of the light curve have most likely occurred. No evidence of H-alpha or O I emission is found. A starspot model is used to generate theoretical light curves which fit those observed. Results indicate that the minimum spotted area is about 8% of the stellar surface area, which suggests that the fractional spotted area is at least 40-80 times greater for DK Dra than the total fractional area on the sun at sunspot maximum. An analysis of multibandpass data shows that the temperature difference between the photosphere and spot is about 1100 K.